Free layer magnetic reader that may have a reduced shield-to-shield spacing

ABSTRACT

A magnetic read apparatus includes a read sensor, a shield structure and a side magnetic bias structure. The read sensor includes a free layer having a side and a nonmagnetic spacer layer. The shield structure includes a shield pinning structure and a shield reference structure. The nonmagnetic spacer layer is between the shield reference structure and the free layer. The shield reference structure is between the shield pinning structure and the nonmagnetic spacer layer. The shield pinning structure includes a pinned magnetic moment in a first direction. The shield reference structure includes a shield reference structure magnetic moment weakly coupled with the pinned magnetic moment. The side magnetic bias structure is adjacent to the side of the free layer.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 14/862,895, filed on Sep. 23, 2015, the entirety of which is incorporated by reference herein.

BACKGROUND

FIG. 1 depicts an air-bearing surface (ABS) view of a conventional read transducer used in magnetic recording technology applications. The conventional read transducer 10 includes shields 12 and 18, insulator 14, magnetic bias structures 16, and sensor 20. The read sensor 20 is typically a giant magnetoresistive (GMR) sensor or tunneling magnetoresistive (TMR) sensor. The read sensor 20 includes an antiferromagnetic (AFM) layer 22, a pinned layer 24, a nonmagnetic spacer layer 26, and a free layer 28. Also shown is a capping layer 30. In addition, seed layer(s) may be used. The free layer 28 has a magnetization sensitive to an external magnetic field. Thus, the free layer 28 functions as a sensor layer for the magnetoresistive sensor 20. If the sensor 20 is to be used in a current perpendicular to plane (CPP) configuration, then current is driven in a direction substantially perpendicular to the plane of the layers 22, 24, 26, and 28. Conversely, in a current-in-plane (CIP) configuration, then conductive leads (not shown) would be provided on the magnetic bias structures 16. The magnetic bias structures 16 are used to magnetically bias the free layer 28.

Although the conventional transducer 10 functions, there are drawbacks. The trend in magnetic recording is to higher density memories. For higher linear densities, the shield-to-shield spacing, SS, and the track width are both desired to be reduced. The conventional shield-to-shield spacing for the transducer is on the order of twenty-two nanometers or more. The conventional read sensor 20 may not adequately read high linear density media. Accordingly, what is needed is a system and method for improving the performance of a magnetic recording read transducer at higher linear densities.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an ABS view of a conventional magnetic recording read transducer.

FIGS. 2A-2C depicts ABS, plan and apex views of an exemplary embodiment of a portion of a magnetic read transducer.

FIG. 3 depicts an ABS view of another exemplary embodiment of a portion of a dual free layer magnetic read transducer.

FIGS. 4A-4D depict ABS views of another exemplary embodiment of a portion of a magnetic read transducer.

FIGS. 5A-5C depict an exemplary embodiment of the magnetic moments of the magnetic read transducer without and with an external magnetic field.

FIGS. 6A-6C depict another exemplary embodiment the magnetic moments of the magnetic read transducer without and with an external magnetic field.

FIG. 7 depicts an ABS view of another exemplary embodiment of a portion of a magnetic read transducer.

FIG. 8 depicts an apex view of another exemplary embodiment of a portion of a magnetic read transducer.

FIG. 9 depicts an apex view of another exemplary embodiment of a portion of a magnetic read transducer.

FIG. 10 depicts an apex view of another exemplary embodiment of a portion of a magnetic read transducer.

FIG. 11 depicts an apex view of another exemplary embodiment of a portion of a magnetic read transducer.

FIG. 12 is flow chart depicting an exemplary embodiment of a method for providing a magnetic recording read transducer.

FIG. 13 is flow chart depicting another exemplary embodiment of a method for providing a magnetic recording read transducer.

DETAILED DESCRIPTION

FIGS. 2A-2C depict ABS, plan and side views of an exemplary embodiment of a portion of a magnetic read transducer 100. For clarity, FIGS. 2A-2C are not to scale. FIG. 2B also depicts the media 180 which may be used with the transducer 100. The read transducer 100 may be part of a read head or may be part of a merged head that also includes a write transducer. The head of which the read transducer 100 is a part is contained in a disk drive having a media 180, a slider and the head coupled with the slider. Further, only a portion of the components of the read transducer 100 are depicted.

The transducer 100 includes top shield 140, insulator 106, shield structure 110, read sensor 120, and side magnetic bias structures 130 that may be separated from the read sensor 120 by an insulating layer 106. The read sensor 120 includes a nonmagnetic spacer 122 and a free layer 124. The nonmagnetic spacer layer 122 may be conductive or an insulating tunneling barrier layer, such as MgO. The free layer 124 is ferromagnetic and may include multiple layers. Thus, the only magnetic layer(s) for the read sensor 120 may be (or be within) the free layer 124. The sensor 120 may thus be termed a “free layer only” read sensor 120. The difference in orientation between the magnetic moment(s) 125 of the free layer 124 and the magnetic moment of a top ferromagnetic layer of the shield reference structure 118 gives rise to a magnetoresistance. The read sensor 120 is, therefore, a giant magnetoresistive (GMR) or tunneling magnetoresistive (TMR) read sensor in the embodiment shown. The resistance of the read sensor 120 may be used to read data. The read sensor 120 may also be configured for high density recording. Thus, in some embodiments, the track width (TW) of the read sensor 120 may be small. For example, the track width may be not more than thirty nanometers.

The side magnetic bias structures 130 may take various forms. In some embodiments, both the magnetic bias structures 130 are soft magnetic layers. For example, the magnetic bias structures 130 may be an alloy, multilayer or other structure that has soft magnetic properties. For example, the magnetic bias structures 130 may include CoFe and/or NiFe. In other embodiments, the magnetic bias structures 130 may be hard bias structures. For example, the magnetic bias structures 130 may be an alloy or multilayer that has a sufficiently high coercivity to have its magnetic moment substantially unchanged during operation of the transducer 100. In other embodiments, the magnetic bias structure 130 have another structure. The magnetic moments 132 of the magnetic bias structures 130 are shown parallel to the cross track direction. The magnetic moments 132 magnetically bias the sensor magnetic moment 125 in the cross track direction.

The shield structure 110 may include an optional bottom shield 112. The bottom shield 112 may be a soft magnetic alloy, such as NiFe. In other embodiments, the bottom shield 112 may be a multilayer structure including but not limited to an antiferromagnetically coupled (AFC) shield. The shield structure 110 also includes a shield pinning structure 114 and a shield reference structure 118. The nonmagnetic spacer layer 122 is between the shield reference structure 118 and the free layer 124. The shield pinning structure 114 may be separated from the shield reference structure 118 by a nonmagnetic coupling layer 116. The nonmagnetic coupling layer 116 mediates the magnetic coupling between the shield reference structure 118 and the shield pinning structure 114. Thus, a magnetic moment of the shield reference structure 116 is weakly magnetically coupled with a magnetic moment of the shield pinning structure 114. The shield pinning structure 114 may be magnetically coupled with the bottom shield 112.

The shield pinning structure 114 may have its magnetic moment(s) strongly pinned, or fixed, in place. For example, the shield pinning structure 114 may include an antiferromagnetic (AFM) layer and a ferromagnetic layer exchanged coupled to the AFM layer. This exchange coupling is generally relatively strong. The magnetic moment(s) of the shield pinning structure 114 may not be responsive to an external field, for example a field due to a media 180. In contrast, the bottom shield 112 has magnetic moment(s) that do respond to an external magnetic field.

The shield reference structure 118 includes at least one ferromagnetic layer. In some embodiments, the shield reference structure 118 includes multiple ferromagnetic layers interleaved with and sandwiching nonmagnetic layers. In other embodiments, a single ferromagnetic layer might be used. Other configurations are possible. In some embodiments, the thickness(es) of the ferromagnetic layers are at least two nanometers and not more than ten nanometers. However, the ferromagnetic layer closest to the shield pining structure 114 may be thicker. For example, this ferromagnetic layer may have a thickness of at least three nanometers and not more than twenty nanometers. The thickness(es) of the nonmagnetic layer(s) within the shield reference structure 118 may be selected that the ferromagnetic layers are antiferromagnetically coupled via a Ruderman-Kasuya-Kittel-Yosida (RKKY) interaction.

The shield reference structure 118 may act as a reference layer for the magnetoresistance of the read sensor 120 and act as a shield. This is because the magnetic moment(s) of the shield reference structure 118 may be considered to be partially pinned and partially free. The magnetic moments of the ferromagnetic layers within the shield reference structure 118 may be strongly coupled to each other. In some embodiments, the ferromagnetic layers are antiferromagnetically coupled with a characteristic magnetic field strength of at least eight hundred and not more than two thousand Oe. The magnetic coupling between the shield reference structure 118 and the shield pinning structure 114 is less than the magnetic coupling between the layers within the shield reference structure 118. For example, the shield reference structure 118 may be coupled with the shield pinning structure 114 with a characteristic field strength of at least three hundred Oe and not more than one thousand five hundred Oe. Thus, the magnetic moments of the shield reference layer 118 are not completely pinned. For example, the shield reference structure 118 has a permeability of at least five and not more than eight hundred. The magnetic moments of the shield reference structure 118 may be at least somewhat responsive to an external magnetic field. However, the magnetic moment(s) of the shield reference structure 118 are sufficiently fixed that a GMR or TMR may be developed between the free layer 124 and the shield reference structure 118.

The magnetic transducer 100 may be suitable for use at higher linear densities. The magnetic moment(s) of the shield reference structure 118 are partially fixed, while the magnetic moment(s) of the free layer 124 respond to the magnetic field of a bit in the media 180 being read. A characteristic magnetoresistance may be developed for the sensor 120 depending upon the direction of the field due to the bit being read and, therefore, information stored in the bit. Thus, the magnetic transducer 100 is capable of reading data using a single free layer sensor 120. Because the magnetic moment(s) of the shield reference structure 118 may at least partially respond to an external field, the shield reference structure 118 may at least partially shield the free layer 124 from the magnetic field of bits not being read. Stated differently, the shield reference structure 118 is part of the shield structure 110. Thus, the spacing between the shields 110 and 140, SS, may be reduced to the thickness of the free layer 124, nonmagnetic spacer layer 122 and capping layer 126. The shield-to-shield spacing may be less than fifteen nanometers. In some embodiments, the shield-to-shield spacing may be on the order of ten nanometers or less. Thus, the shield-to-shield spacing of the magnetic transducer 100 may be reduced. Consequently, the magnetic transducer 100 may be suitable for high linear and/or areal density magnetic recording applications.

FIG. 3 depicts a plan view of another embodiment of a magnetic read transducer 100′. For clarity, FIG. 3 is not to scale. The read transducer 100′ may be part of a read head or may be part of a merged head that also includes a write transducer. The head of which the read transducer 100′ is a part is part of a disk drive having a media 180, a slider and the head coupled with the slider. The transducer 100′ corresponds to the transducer 100. Consequently, analogous components are labeled similarly. For example, the transducer 100′ includes a read sensor 120 including a free layer and a nonmagnetic spacer layer analogous to the layers 124 and 122. The magnetic transducer 100 also includes side bias structures 130 having magnetic moments 132, insulator 106, shield structure (not shown) and shield (not shown) that are analogous to the structures 130, 132, 106, 110 and 140 depicted in FIGS. 2A-2C.

In addition, the magnetic transducer 100′ includes a rear bias structure 150 that may be separated from the read sensor 120 and side bias structure 130 by a nonmagnetic insulator 151. The read sensor 120 is between the ABS and the rear magnetic bias structure 150. The rear bias structure 150 is shown having a width in the cross-track direction that is greater than the track width. In other embodiments, the rear bias structure 150 may have a width that is substantially equal to the track width, TW, of the read sensor 120. In some embodiments, this is because the sensor 120 and rear bias structure 150 are defined in the cross-track direction using a single mask. Stated differently, the rear bias structure 160 and sensor 110 may be self-aligned. In other embodiments, the rear bias structure 150 may extend to or past the outside edges of the bias structures 130 in the cross-track direction. In some embodiments, the length of the rear bias structure 150 in the stripe height direction is greater than the width in the cross-track direction. Thus, the rear bias structure 150 may have a shape anisotropy that is perpendicular to the ABS. The rear bias structure 150 may include magnetically soft and/or magnetically hard materials.

The rear magnetic bias structure 150 magnetically biases the read sensor 120 in a stripe height direction perpendicular to the ABS. The magnetic moment 152 of the rear bias structure 150 is thus shown as oriented toward the ABS. In other embodiments, the magnetic moment 152 may be oriented in the opposite direction. Because of the combination of the side bias structures 130 and the rear bias structure 150, the magnetic moment 125′ of the read sensor 120 is canted from the cross-track direction in the absence of an external field.

The magnetic transducer 100′ may be suitable for use at higher linear densities. The magnetic moment(s) of the shield reference structure (not shown in FIG. 3) are partially fixed, while the magnetic moment 125′ of the free layer/sensor 120 responds to the magnetic field of a bit in the media 180 being read. A characteristic magnetoresistance may be developed for the sensor 120 depending upon the direction of the field due to the bit being read. Thus, the magnetic transducer 100′ is capable of reading data using a single free layer sensor 120. Because the magnetic moment(s) of the shield reference structure may at least partially respond to an external field, the shield reference structure may at least partially shield the free layer/sensor 120 from the magnetic field of bits not being read. Stated differently, the shield reference structure is part of the shield structure. The spacing between the shields may be reduced to the thickness of the free layer, nonmagnetic spacer layer and capping layer. The shield-to-shield spacing may be less than fifteen nanometers. In some embodiments, the shield-to-shield spacing may be on the order of ten nanometers or less. Thus, the shield-to-shield spacing of the magnetic transducer 100′ may be reduced. Consequently, the magnetic transducer 100′ may be suitable for high linear and/or areal density magnetic recording applications.

FIGS. 4A-4D depict various views of exemplary embodiments of a portion of a magnetic read transducer 100″. For clarity, FIGS. 4A-4D are not to scale. FIG. 4A depicts an ABS view of the magnetic transducer 100″. FIGS. 4B-4D depict embodiments of the magnetic transducer 100″ in the absence of an external field. FIG. 4B depicts the magnetic layers of the transducer 100″ if no rear magnetic bias is used. FIG. 4C depicts the magnetic layers of the transducer 100″ in the presence of a rear magnetic bias. FIG. 4D depicts another embodiment of the magnetic layers of the transducer 100″ if a different magnetic bias is used. The read transducer 100″ may be part of a read head or may be part of a merged head that also includes a write transducer. The head of which the read transducer 100″ is a part is contained in a disk drive having a media (not shown in FIGS. 4A-4D), a slider and the head coupled with the slider. Further, only a portion of the components of the read transducer 100″ are depicted.

The transducer 100″ corresponds to the transducer(s) 100 and/or 100′. Consequently, analogous components are labeled similarly. For example, the transducer 100″ includes a read sensor 120 including a free layer 124 and a nonmagnetic spacer layer 122 analogous to the layers 124 and 122. The magnetic transducer 100″ also includes side bias structures 130 having magnetic moments 132, insulator 106, shield structure 110′ and shield 140′ that are analogous to the structures 130, 132, 106, 110 and 140 depicted in FIGS. 2A-2C. Thus, the components 106, 110′, 112, 114′, 116, 118′, 120, 122, 124, 126, 130 and 140′ have an analogous structure and function to the corresponding components described above. For example, the sensor 120 is a free layer only sensor including the free layer 124 and nonmagnetic spacer layer 122.

The shield 140′ includes a ferromagnetic layer 142, a nonmagnetic layer 144, another ferromagnetic layer 146, an AFM layer 147 and a top shield 148. The magnetic layers 142 and 146 are antiferromagnetically coupled via an RKKY interaction. The ferromagnetic layer 146 is exchange coupled to the AFM layer 147. Thus, the shield 140′ is an AFC shield. In other embodiments, the shield 140′ may have a different structure.

The shield structure 110′ includes a bottom shield 112, a shield pinning structure 114′, a nonmagnetic coupling layer 116 and a shield reference structure 118′. The shield pinning structure 114′ including a pinning layer 160 and a ferromagnetic layer 162. The pining layer 160 may be an AFM layer, such as IrMn. The magnetic layer 162 has its magnetic moment pinned by the exchange coupling with the pinning layer 160. This can be seen in FIGS. 4B, 4C and 4D. The magnetic moment 163 of the ferromagnetic layer 162 of the shield pinning structure 114′ may not be responsive to an external field, for example a field due to a media.

The shield reference structure 118′ includes two ferromagnetic layers 170 and 174 interleaved with and sandwiching a nonmagnetic layer 172. The nonmagnetic layer 172 may be a Ru layer. However, other material(s) might be used. The ferromagnetic layers 140 and 174 are termed reference layers because the orientation of the free layer magnetic moment 125/125′ with respect to the magnetic moment 171 results in the magnetoresistance of the read sensor 120. In some embodiments, the reference layer 170 is at least two nanometers and not more than ten nanometers thick. The reference layer 174 may have a thickness of at least three nanometers and not more than twenty nanometers. The thickness of the nonmagnetic layer 172 may be selected that the reference layers 170 and 174 are antiferromagnetically coupled via a RKKY interaction. Thus, the coupling between the reference layers 170 and 174 may be relatively strong. In some embodiments, the reference layers 170 and 174 are antiferromagnetically coupled with a characteristic magnetic field strength of at least eight hundred and not more than two thousand Oe. The directions of the magnetic moments 171 and 175 of the reference layers 170 and 174 may be responsive to an external field. For example, the permeability of the shield reference structure 118′ may be at least five and not more than eight hundred.

The nonmagnetic coupling layer 116 has a thickness that may be used to set the strength of the coupling between the magnetic layer 162 and the magnetic layer 174. The magnetic coupling between the layers 162 and 174 is less than the magnetic coupling between the reference layers 170 and 174. For example, the magnetic layer 162 may be coupled with the reference layer 174 with a characteristic field strength of at least three hundred Oe and not more than one thousand five hundred Oe. Thus, the magnetic moments 171 and 175 of the shield reference structure 118′ are not completely pinned. The magnetic moments 171 and 175 of the reference layers 172 and 174 are strongly coupled. However, the reference layer 174 is not strongly magnetically coupled to the layer 162. Thus, the magnetic moments 171 and 175 of the reference layers 170 and 174, respectively, may be at least partially responsive to an external field. Thus, the reference layers 170 and 174 are part of the shield.

Although described as separate structures, the structures 114′, 116 and 118′ may be considered to form an antiferromagnetically coupled shield structure. Thus, the ferromagnetic layer 162 of the pinning structure 114′ may be considered to be a third reference layer for the shield structure 110′. In such a shield structure 110′, the third reference layer 162 is strongly coupled to the pinning layer 160. However, the second reference layer 174 is weakly coupled with the third reference layer 162.

FIG. 4B depicts one embodiment of the magnetic layers of the transducer 100″ in the absence of a rear bias structure. The free layer 124 has a magnetic moment 125 that is magnetically biased by the moments 132 of the side bias structures 130. Thus, the free layer magnetic moment 125 is in the cross-track direction. As can also be seen in FIG. 4B, the magnetic moment 163 of the ferromagnetic layer 162 is coupled to the direction of orientation some of the magnetic moments 161 of the pinning layer 160. The magnetic moments 171 and 175 of the layers 170 and 174 are antiferromagnetically coupled. The moment 175 of the layers 174 is weakly coupled with the moment 163 of the layer 162.

FIG. 4C depicts one embodiment of the magnetic layers of the transducer 100″ in the presence of a rear bias structure 150 having magnetic moments 152. The free layer 124 has a magnetic moment 125′ that is magnetically biased by the moments 132 of the side bias structures 130 and by the magnetic moment 152 of the rear bias structure 150. In the embodiment shown, the magnetic bias due to the rear bias structure 150 is sufficiently strong that the magnetic moment 125′ is canted from the cross-track direction. As can also be seen in FIG. 4C, the magnetic moment 163 of the ferromagnetic layer 162 is coupled to the direction of orientation some of the magnetic moments 161 of the pinning layer 160. The magnetic moments 171 and 175 of the layers 170 and 174 are antiferromagnetically coupled. The moment 175 of the layers 174 is weakly coupled with the moment 163 of the layer 162.

FIG. 4D depicts another embodiment of the magnetic layers of the transducer 100″ in the presence of a rear bias structure 150 having magnetic moments 152. The free layer 124 has a magnetic moment 125 that is magnetically biased by the moments 132 of the side bias structures 130 and by the magnetic moment 152 of the rear bias structure 150. In the embodiment shown, the magnetic bias due to the rear bias structure 150 is sufficiently weak that the magnetic moment 125 remains in the cross-track direction. As can also be seen in FIG. 4D, the magnetic moment 163 of the ferromagnetic layer 162 is coupled to the direction of orientation of the magnetic moments 161 of the pinning layer 160. The magnetic moments 171 and 175 of the layers 170 and 174 are antiferromagnetically coupled. The moment 175 of the layers 174 is weakly coupled with the moment 163 of the layer 162.

The magnetic transducer 100″ may be suitable for use at higher linear densities. The magnetic moments 171 and 175 of the shield reference structure 118′ are partially fixed. The magnetic moment 125/125′ of the free layer 124 responds to the magnetic field of a bit in the media being read. Thus, a magnetoresistance may be developed for the sensor 120 depending upon the information stored in the bit. Thus, the magnetic transducer 100″ is capable of reading data using a single free layer sensor 120. Because the magnetic moment 171 and 175 of the shield reference structure 118′ may at least partially respond to an external field, the shield reference structure 118′ may at least partially shield the free layer 124 from the magnetic field of bits not being read. The spacing between the shields 110′ and 140′, SS, may be reduced to the thickness of the free layer 124, nonmagnetic spacer layer 122 and capping layer 126. The shield-to-shield spacing may be less than fifteen nanometers. In some embodiments, the shield-to-shield spacing may be on the order of ten nanometers or less. Thus, the shield-to-shield spacing of the magnetic transducer 100″ may be reduced. Consequently, the magnetic transducer 100″ may be suitable for high linear and/or density magnetic recording applications.

Operation of the magnetic transducers 100, 100′ and/or 100″ may be understood with respect to FIGS. 5A-5C and FIGS. 6A-6C. FIGS. 5A, 5B and 5C are charts 200 depicting the magnetic moments of the free layer 120 and the first reference layer 170 with no external field, with an external field in one direction and with an external field in the opposite direction. Thus, FIGS. 5B and 5C may be viewed as depicting the influence of bits storing a logical “0” and a logical “1”, respectively, or vice versa. FIGS. 5A-5C correspond to a transducer 100/100′/100″ which either does not have a rear bias 150 or for which the rear bias is sufficiently weak that the free layer magnetic moment 202 is not canted from the cross-track direction when no external field is applied. In other words, FIGS. 5A-5C may be viewed as representing the situations shown in FIG. 4B or FIG. 4D. In FIGS. 5A, 5B and 5C, the free layer magnetic moment is denoted by reference numeral 202, while the first reference layer 170 magnetic moment is denoted by the reference numeral 204.

In FIG. 5A, the free layer magnetic moment 202 is in the cross-track direction. Thus, the angle at which the free layer is canted from the cross-track direction, θ₁, is zero. The first reference layer magnetic moment 204 is at an angle θ₁, from the cross track direction. In some embodiments, θ₁ is at least forty degrees and not more than fifty degrees. The first reference layer magnetic moment 204 may thus be directed at a nonzero angle from the ABS. Thus, the free layer magnetic moment 202 is at an angle α₁ from the first reference layer magnetic moment 204 when no external field is applied.

FIG. 5B depicts the situation when the external field is in the stripe height direction (towards the ABS). Both the free layer magnetic moment 202 and the first reference layer magnetic moment 204 have responded to the external field. Thus, the free layer magnetic moment 202 is at a new angle, θ₂ from the cross track direction. Similarly, the reference layer magnetic moment is at angle ϕ₂ from the cross-track direction. In FIG. 5B, the dashed line denotes the orientation of the reference layer magnetic moment 204 without the external field. Thus, the free layer magnetic moment 202 may be seen as more free to change in response to the external magnetic field. The free layer magnetic moment 202 and the first reference layer magnetic moment 204 are at a new angle, α₂, which is smaller than α₁. Therefore, the magnetoresistance of the read sensor 120 is different for the configuration shown in FIG. 5B than for the configuration shown in FIG. 5A.

FIG. 5C depicts the situation when the external magnetic field is in the opposite direction to that shown in FIG. 5B. Thus, the free layer magnetic moment 202 forms the angle θ₃ with respect to the cross track direction. The free layer magnetic moment 202 has again changed orientation due to the external field. Similarly, the first reference layer magnetic moment 204 has slightly changed orientation due to the external field. Thus, the magnetic moments 202 and 204 form angles θ₃ and ϕ₃, respectively, with the cross track direction. The dashed line in FIG. 5C indicates the orientation of the first reference layer magnetic moment 204 in the absence of an external field. The free layer magnetic moment 202 and the first reference layer magnetic moment 204 form a new angle, α₃. This angle is different from α₁ and from α₂. Because the magnetoresistance of the sensor 120 depends upon the angle between the free layer magnetic moment 202 and the reference layer magnetic moment 204, the sensor 120 has different magnetoresistances depending on the external field from the media. Thus, the magnetic transducer 100, 100′ and/or 100″ may read data from the media. In addition, because the first reference layer magnetic moment 204 changes direction based on the applied field, the first reference layer 170 is part of the shield 110/110′. Consequently, the shield-to-shield spacing may be reduced. The benefits of the magnetic transducers 100, 100′ and/or 100″ discussed above may, therefore, be achieved.

FIGS. 6A, 6B and 6C are charts 210 depicting the magnetic moments of the free layer 120 and the first reference layer 170 with no external field, with an external field in one direction and with an external field in the opposite direction. Thus, FIGS. 6B and 6C may be viewed as depicting the influence of bits storing a logical “0” and a logical “1”, respectively, or vice versa. FIGS. 6A-6C correspond to a transducer 100/100′/100″ which has a rear bias 150 that is sufficiently strong that the free layer magnetic moment 202 is canted from the cross-track direction when no external field is applied. In other words, FIGS. 6A-6C may be viewed as representing the situations shown in FIG. 4C. In FIGS. 6A, 6B and 6C, the magnetic moment of the free layer 124 is denoted by reference numeral 212, while the magnetic moment of the first reference layer 170 is denoted by the reference numeral 214.

In FIG. 6A, the free layer magnetic moment 212 is canted from the cross-track direction by an angle, θ₁′. The first reference layer magnetic moment 214 is at an angle ϕ₁′, from the cross track direction. In some embodiments, ϕ₁′ is at least forty degrees and not more than fifty degrees. The first reference layer magnetic moment 214 may thus be directed at an angle from the ABS. Thus, the free layer magnetic moment 212 is at an angle α₁′ from the first reference layer magnetic moment 214 when no external field is applied. In the embodiment shown, α₁′ is ninety degrees. However, other values are possible.

FIG. 6B depicts the situation when the external field is in the stripe height direction (towards the ABS). Both the free layer magnetic moment 212 and the first reference layer magnetic moment 214 have responded to the external field. Thus, the free layer magnetic moment 212 is at a new angle, θ₂′ from the cross track direction. Similarly, the reference layer magnetic moment is at angle ϕ₂′ from the cross-track direction. In FIG. 6B, the dashed line denotes the orientation of the magnetic moment 214 without the external field. Thus, the free layer magnetic moment 212 may be seen as more free to change in response to the external magnetic field. The free layer magnetic moment 212 and the first reference layer magnetic moment 214 are at a new angle, α₂′ which is smaller than α₁′.

FIG. 6C depicts the situation when the external magnetic field is in the opposite direction to that shown in FIG. 6B. Thus, the free layer magnetic moment 212 forms the angle θ₃′ with respect to the cross-track direction. The free layer magnetic moment 212 has again changed orientation due to the external field. Similarly, the first reference layer magnetic moment 201 has slightly changed orientation due to the external field. Thus, the magnetic moments 212 and 214 form angles θ₃′ and ϕ₃′, respectively, with the cross-track direction. The dashed line in FIG. 6C indicates the orientation of the first reference layer magnetic moment 214 in the absence of an external field. The free layer magnetic moment 212 and the first reference layer magnetic moment 214 form a new angle, α₃′. This angle is different from α₁′ and from α₂′ Because the magnetoresistance of the sensor 120 depends upon the angle between the free layer magnetic moment 212 and the reference layer magnetic moment 214, the sensor 120 has different magnetoresistances depending on the external field from the media. Thus, the magnetic transducer 100, 100′ and/or 100″ may read data from the media. In addition, because the first reference layer magnetic moment 214 changes based on the applied field, the first reference layer 170 is part of the shield 110/110′. Consequently, the shield-to-shield spacing may be reduced. The benefits of the magnetic transducers 100, 100′ and/or 100″ discussed above may, therefore, be achieved.

FIG. 7 depicts an ABS view of exemplary embodiments of a portion of another magnetic read transducer 100′″. For clarity, FIG. 7 is not to scale. The read transducer 100′″ may be part of a read head or may be part of a merged head that also includes a write transducer. The head of which the read transducer 100′″ is a part is contained in a disk drive having a media (not shown in FIG. 7), a slider and the head coupled with the slider. Further, only a portion of the components of the read transducer 100′″ are depicted. Thus, the transducer 100″ may include or may omit a rear bias structure analogous to the rear magnetic bias structure 150.

The transducer 100′″ corresponds to the transducer(s) 100, 100′ and/or 100″. Consequently, analogous components are labeled similarly. For example, the transducer 100′″ includes a read sensor 120 including a free layer 124 and a nonmagnetic spacer layer 122 analogous to the layers 124 and 122. The magnetic transducer 100′″ also includes side bias structures 130 having magnetic moments 132, insulator 106 which may be MgO, shield structure 110″ and shield 140′ that are analogous to the structures 130, 132, 106, 110/110′ and 140/140′. Thus, the components 106, 110″, 112, 114″, 116, 118′, 120, 122, 124, 126, 130 and 140′ have an analogous structure and function to the corresponding components described above. For example, the sensor 120 is a free layer only sensor including the free layer 124 and nonmagnetic spacer layer 122.

The shield structure 110″ includes a bottom shield 112, a shield pinning structure 114″, a nonmagnetic coupling layer 116 and a shield reference structure 118′. The shield reference structure 118′ includes two ferromagnetic layers 170 and 174 interleaved with and sandwiching a nonmagnetic layer 172. The ferromagnetic layers 140 and 174 are termed reference layers because the orientation of the free layer magnetic moment 125/125′ with respect to the magnetic moment 171 results in the magnetoresistance of the read sensor 120. The structure and function of the components of the shield reference structure 118′ are analogous to those discussed above.

The shield pinning structure 114″ including a pinning layer 160′ and a ferromagnetic layer 162′. The structure and function of the pinning layers 160′ and ferromagnetic/third reference layer 162′ are analogous to those of the layers 160 and 162, respectively. However, in the embodiment shown, the layers 162 and 160′ are wider in the cross-track direction. Thus, the widths of the layers 160′ and 162′ may be defined in a separate step from the layers 170, 172, 174 and 116.

The magnetic transducer 100′″ may be suitable for use at higher areal densities. The magnetic moments of the shield reference structure 118′ are partially fixed. The magnetic moment of the free layer 124 responds to the magnetic field of a bit in the media being read. Thus, a magnetoresistance may be developed for the sensor 120 depending upon the information stored in the bit. Thus, the magnetic transducer 100′″ is capable of reading data using a single free layer sensor 120. Because the magnetic moment of the shield reference structure 118″ may at least partially respond to an external field, the shield reference structure 118″ may at least partially shield the free layer 124 from the magnetic field of bits not being read. The spacing between the shields 110″ and 140′, SS, may be reduced to the thickness of the free layer 124, nonmagnetic spacer layer 122 and capping layer 126. The shield-to-shield spacing may be less than fifteen nanometers. In some embodiments, the shield-to-shield spacing may be on the order of ten nanometers or less. Thus, the track width and the shield-to-shield spacing of the magnetic transducer 100″ may be reduced. Consequently, the magnetic transducer 100′″ may be suitable for high density magnetic recording applications.

FIG. 8 depicts an apex view of exemplary embodiments of a portion of another magnetic read transducer 300. For clarity, FIG. 8 is not to scale. The read transducer 300 may be part of a read head or may be part of a merged head that also includes a write transducer. The head of which the read transducer 300 is a part is contained in a disk drive having a media (not shown in FIG. 8), a slider and the head coupled with the slider. Further, only a portion of the components of the read transducer 300 are depicted. Thus, the transducer 300 may include or may omit a rear bias structure analogous to the rear magnetic bias structure 150.

The transducer 300 corresponds to the transducer(s) 100, 100′, 100″ and/or 100′″. Consequently, analogous components are labeled similarly. For example, the transducer 300 includes a read sensor 320 including a free layer 324 and a nonmagnetic spacer layer 322 analogous to the layers 124 and 122, respectively. The magnetic transducer 300 includes side bias structures (not shown) and insulator (not shown) analogous to the side bias structures 130 and insulator 106, respectively. Although not shown, the magnetic transducer 300 may also include a capping layer analogous to the capping layer 126. Further, the magnetic read transducer 300 includes a shield structure 310 and shield 340 that are analogous to the structures 110/110′/110″ and 140/140′, respectively. Thus, the components 310, 312, 314, 316, 318, 320, 322, 324 and 340 have an analogous structure and function to the corresponding components described above. For example, the sensor 120 is a free layer only sensor including the free layer 124 and nonmagnetic spacer layer 122.

The shield structure 310 includes a bottom shield 312, a shield pinning structure 314, a nonmagnetic coupling layer 316 and a shield reference structure 318 analogous to the structures 112, 114/114′/114″, 116 and 118/118′. Thus, the shield reference structure 318 includes reference layers 370 and 374 separated by nonmagnetic layer 372. The layers 370, 372 and 374 are analogous to the layers 170, 172 and 174, respectively. In the embodiment shown, the shield reference structure. The shield pinning structure 314 includes a pinning layer 360 that may be an AFM layer and magnetic layer 362. The layer 362 may be considered a third reference layer. The layers 360 and 362 are analogous to the layers 160/160′ and 162/162′, respectively. Thus, the magnetic transducer 300 operates in an analogous manner to the transducer(s) 100, 100′, 100″ and/or 100′″.

In addition, the magnetic transducer 300 has an extended length in the stripe height direction. In particular, portions of the reference layers 370, 374 and 362 are longer in the stripe height direction than the free layer 324. In addition, the AFM layer 360 is longer in the stripe height direction. Because of its increased volume, the AFM layer 360 may be more magnetically stable. Pinning of the magnetic layer/third reference layer 362 may be improved. Stability of the reference layers 370 and 374 may also be improved.

The magnetic transducer 300 may share the benefits of the magnetic transducer(s) 100, 100′, 100″ and/or 100′″. The spacing between the shields 310 and 340, SS, may be reduced to the thickness of the free layer 324, nonmagnetic spacer layer 322 and capping layer (if present). The shield-to-shield spacing may be less than fifteen nanometers. In some embodiments, the shield-to-shield spacing may be on the order of ten nanometers or less. Thus, the track width and the shield-to-shield spacing of the magnetic transducer 300 may be reduced. Consequently, the magnetic transducer 300 may be suitable for high density magnetic recording applications.

FIG. 9 depicts an apex view of exemplary embodiments of a portion of another magnetic read transducer 300′. For clarity, FIG. 9 is not to scale. The read transducer 300′ may be part of a read head or may be part of a merged head that also includes a write transducer. The head of which the read transducer 300′ is a part is contained in a disk drive having a media (not shown in FIG. 9), a slider and the head coupled with the slider. Further, only a portion of the components of the read transducer 300′ are depicted. Thus, the transducer 300′ may include or may omit a rear bias structure analogous to the rear magnetic bias structure 150.

The transducer 300′ corresponds to the transducer(s) 300, 100, 100′, 100″ and/or 100′″. Consequently, analogous components are labeled similarly. For example, the transducer 300′ includes components 310′, 312, 314, 316, 318′, 320, 322, 324, 340, 360, 362, 374, 372′ and 370′ that have an analogous structure and function to the corresponding components described above. Thus, the magnetic transducer 300′ operates in an analogous manner to the transducer(s) 300, 100, 100′, 100″ and/or 100′″.

In addition, the magnetic transducer 300′ has an extended length in the stripe height direction. Although the first reference layer 370′ has been milled through, particular, portions of the reference layers 374 and 362 are longer in the stripe height direction than the free layer 324. In addition, the AFM layer 360 is longer in the stripe height direction. Because of its increased volume, the AFM layer 360 may be more magnetically stable. Pinning of the magnetic layer/third reference layer 362 may be improved. Stability of the reference layer and 374 may also be improved.

The magnetic transducer 300′ may share the benefits of the magnetic transducer(s) 300, 100, 100′, 100″ and/or 100′″. The spacing between the shields 310′ and 340, SS, may be reduced in the manner described above. Consequently, the magnetic transducer 300′ may be suitable for high density magnetic recording applications.

FIG. 10 depicts an apex view of exemplary embodiments of a portion of another magnetic read transducer 300″. For clarity, FIG. 10 is not to scale. The read transducer 300″ may be part of a read head or may be part of a merged head that also includes a write transducer. The head of which the read transducer 300″ is a part is contained in a disk drive having a media (not shown in FIG. 10), a slider and the head coupled with the slider. Further, only a portion of the components of the read transducer 300″ are depicted. Thus, the transducer 300″ may include or may omit a rear bias structure analogous to the rear magnetic bias structure 150.

The transducer 300″ corresponds to the transducer(s) 300, 300′, 100, 100′, 100″ and/or 100″. Consequently, analogous components are labeled similarly. For example, the transducer 300′ includes components 310″, 312, 314, 316, 318″, 320, 322, 324, 340, 360, 362, 374′, 372″ and 370′ that have an analogous structure and function to the corresponding components described above. Thus, the magnetic transducer 300″ operates in an analogous manner to the transducer(s) 300, 300′, 100, 100′, 100″ and/or 100″.

The magnetic transducer 300″ has an extended length in the stripe height direction. Although the layers 370′, 372′ and 374′ have been milled through, particular, portions of the reference layers 374 and 362 are longer in the stripe height direction than the free layer 324. In addition, the AFM layer 360 is longer in the stripe height direction. Because of its increased volume, the AFM layer 360 may be more magnetically stable. Pinning of the magnetic layer/third reference layer 362 may be improved.

The magnetic transducer 300″ may share the benefits of the magnetic transducer(s) 300, 300′, 100, 100′, 100″ and/or 100′″. The spacing between the shields 310″ and 340, SS, may be reduced in the manner described above. Consequently, the magnetic transducer 300″ may be suitable for high density magnetic recording applications.

FIG. 11 depicts an apex view of exemplary embodiments of a portion of another magnetic read transducer 300′″. For clarity, FIG. 11 is not to scale. The read transducer 300′″ may be part of a read head or may be part of a merged head that also includes a write transducer. The head of which the read transducer 300′″ is a part is contained in a disk drive having a media (not shown in FIG. 10), a slider and the head coupled with the slider. Further, only a portion of the components of the read transducer 300″ are depicted. Thus, the transducer 300′″ may include or may omit a rear bias structure analogous to the rear magnetic bias structure 150.

The transducer 300′″ corresponds to the transducer(s) 300, 300′, 300″, 100, 100′, 100″ and/or 100′″. Consequently, analogous components are labeled similarly. For example, the transducer 300′ includes components 310′″, 312, 314′, 316′, 318″, 320, 322, 324, 340, 360, 362′, 374′, 372″ and 370′ that have an analogous structure and function to the corresponding components described above. Thus, the magnetic transducer 300′″ operates in an analogous manner to the transducer(s) 300, 300′, 300″, 100, 100′, 100″ and/or 100′″.

The magnetic transducer 300′″ has an extended length in the stripe height direction. The AFM layer 360 is longer in the stripe height direction. Because of its increased volume, the AFM layer 360 may be more magnetically stable. Pinning of the magnetic layer/third reference layer 362 may be improved.

The magnetic transducer 300′″ may share the benefits of the magnetic transducer(s) 300, 300′, 300″, 100, 100′, 100″ and/or 100″. The spacing between the shields 310′″ and 340, SS, may be reduced in the manner described above. Consequently, the magnetic transducer 300′″ may be suitable for high density magnetic recording applications.

The magnetic transducers 100, 100′, 100″, 100″, 300, 300′, 300″ and 300′″ have been shown with various configurations to highlight particular features, such as differences in geometries. One of ordinary skill in the art will readily recognize that two or more of these features may be combined in various manners consistent with the method and system described herein that are not explicitly depicted in the drawings.

FIG. 12 is an exemplary embodiment of a method 400 for providing a read transducer. For simplicity, some steps may be omitted, interleaved, combined, have multiple substeps and/or performed in another order unless otherwise specified. The method 400 is described in the context of providing a magnetic recording disk drive and transducer 100. However, the method 400 may be used in fabricating the transducer 100, 100′, 100″, 100′″, 300, 300′, 300″ and/or 300′″. The method 400 may be used to fabricate multiple magnetic read heads at substantially the same time. The method 400 may also be used to fabricate other magnetic recording transducers. The method 400 is also described in the context of particular layers. A particular layer may include multiple materials and/or multiple sub-layers. The method 400 is described in the context of a disk drive. However, the method may be used in other applications employing a magnetoresistive and bias structures. The method 400 also may start after formation of other portions of the magnetic recording transducer.

A shield structure 110 is provided, via step 402. Step 402 thus includes providing the shield reference structure 118 and the shield pinning structure 114. The bottom shield 112 and the nonmagnetic coupling layer 116 may also be provided as part of step 402. Step 402 typically includes depositing the desired layers, defining their edges as well as one or more anneals to set the desired magnetic bias direction(s).

The read sensor 120 is provided, via step 404. Step 404 may include depositing a stack of layers for the read sensor and defining the read sensor in the cross-track and stripe height directions. Thus, the nonmagnetic layer 122 and the free layer 124 are provided in step 404. The capping layer 126 may also be fabricated. Further, the insulating layer 106 may also be provided.

The side bias structures 130 are provided, via step 406. Step 406 may include depositing the magnetic material(s) for the side bias structures 130 and planarizing the magnetic transducer.

The rear bias structure 150 may optionally be provided, via step 408. Step 408 may be performed after the sensor 120 has been defined in at least the stripe height direction. Thus, at least part of step 408 is performed after at least part of step 404. The top shield 140 is also provided, via step 410.

Using the method 400, the transducers 100, 100′, 100″, 100′″, 300, 300′, 300″ and/or 300′″ may be fabricated. Thus, the benefits of one or more of the transducers 100, 100′, 100″, 100′″, 300, 300′, 300″ and/or 300′″ may be achieved.

FIG. 13 is an exemplary embodiment of a method 420 for providing the shield structure 110, 110′, 110″, 310, 310′, 310″ and/or 310′″ of a read transducer. For simplicity, some steps may be omitted, interleaved, combined, have multiple substeps and/or performed in another order unless otherwise specified. The method 420 is described in the context of providing a magnetic recording disk drive and transducer 100″. However, the method 210 may be used in fabricating the transducer 100, 100′, 100″, 100′″, 300, 300′, 300″ and/or 300′″. The method 420 may be used to fabricate multiple magnetic read heads at substantially the same time. The method 420 may also be used to fabricate other magnetic recording transducers. The method 420 is also described in the context of particular layers. A particular layer may include multiple materials and/or multiple sub-layers. The method 420 is described in the context of a disk drive. However, the method may be used in other applications employing a magnetoresistive and bias structures. The method 420 also may start after formation of other portions of the magnetic recording transducer.

The pinning layer 160 is deposited, via step 422. Step 422 may include depositing an AFM layer, such as IrMn. The pinning layer 160 may also be annealed in a magnetic field. However, the annealing may take place after deposition of other portions of the magnetic transducer 100′.

The magnetic/third reference layer 162 may be provided, via step 424. The magnetic/third reference layer 162 may be deposited directly on the pinning layer 160. Thus, the layers 160 and 162 may be exchange coupled. As a result, the magnetic moment of the layer 162 may be substantially fixed. The shield pinning structure 114′ may thus be fabricated in steps 422 and 424.

The nonmagnetic coupling layer 116 is provided, via step 426. Step 426 includes providing a desired thickness of the nonmagnetic coupling layer 116. Configuring the thickness of the layer 116 in step 426 allows for the desired magnetic coupling to be obtained between the pinning structure 114′ and the reference structure 118′.

The second reference layer 174 is provided, via step 428. Step 428 includes depositing desired ferromagnetic material(s) at the desired thickness(es). The nonmagnetic layer 172 is provided, via step 430. Step 430 includes depositing the nonmagnetic layer 172 at the thickness for the desired RKKY coupling. The first reference layer 170 may then be provided, via step 432. Step 432 includes depositing desired ferromagnetic material(s) at the desired thickness(es). Steps 430 and 432 may be repeated to provide a shield reference structure having more layers. Step(s) 432, 430 and/or 428 may also include milling the layer(s) 170, 172 and 174 to provide the desired width(s) in the cross-track direction and the desired length(s) in the stripe height direction.

Thus, the magnetic transducer 100′ may be fabricated. The method 420 may also be used to fabricate the transducer(s) 100, 100″, 100′″, 300, 300′, 300″ and/or 300′″. Thus, the benefits of one or more of the transducers 100, 100′, 100″, 100′″, 300, 300′, 300″ and/or 300′″ may be achieved. Consequently, shield-to-shield spacing for the transducer 100, 100′, 100″, 100′″, 300, 300′, 300″ and/or 300′″ may be reduced. Thus, readers for higher areal density disk drives may be fabricated. 

What is claimed is:
 1. A magnetic read apparatus comprising: a read sensor; a shield structure comprising: a shield pinning structure; a shield reference structure; and a nonmagnetic coupling layer between the shield pinning structure and the shield reference structure; and a top shield structure comprising: a first ferromagnetic layer; a second ferromagnetic layer; a nonmagnetic layer between the first ferromagnetic layer and the second ferromagnetic layer; an antiferromagnetic layer; and a top shield, wherein the antiferromagnetic layer is between the top shield and the second ferromagnetic layer, wherein the read sensor is between the top shield structure and the shield structure.
 2. The magnetic read apparatus of claim 1, wherein the shield pinning structure comprises a pinning layer and a magnetic layer, wherein the magnetic layer abuts the nonmagnetic coupling layer.
 3. The magnetic read apparatus of claim 1, wherein the shield reference structure comprises a first magnetic layer, a second magnetic layer, and a nonmagnetic layer between the first magnetic layer and the second magnetic layer, wherein the first magnetic layer abuts a nonmagnetic spacer layer of the read sensor and the second magnetic layer abuts the nonmagnetic coupling layer.
 4. The magnetic read apparatus of claim 1, wherein the shield structure further comprises a bottom shield located under and abutting the shield pinning structure.
 5. The magnetic read apparatus of claim 1, further comprising a side magnetic bias structure located on either side of the read sensor adjacent to a free layer of the read sensor.
 6. The magnetic read apparatus of claim 5, wherein the side magnetic bias structure is separated from the read sensor on the either side by an insulating layer.
 7. The magnetic read apparatus of claim 1, further comprising a rear bias structure, wherein the read sensor is between an air bearing surface of the magnetic read apparatus and the rear bias structure, and wherein the read sensor is separated from the rear bias structure by a nonmagnetic insulator layer.
 8. The magnetic read apparatus of claim 7, wherein the rear bias structure has a width in a cross-track direction that is greater than a track width of the read sensor in the cross-track direction, wherein the cross-track direction extends along a plane that is parallel to the air bearing surface.
 9. The magnetic read apparatus of claim 1, wherein the shield pinning structure is wider than the shield reference structure in a cross-track direction that is parallel to an air bearing surface.
 10. A magnetic read apparatus comprising: a read sensor comprising a free layer and a nonmagnetic spacer layer; a top shield structure comprising: a first ferromagnetic layer; a second ferromagnetic layer; a nonmagnetic layer between the first ferromagnetic layer and the second ferromagnetic layer; an antiferromagnetic layer; and a top shield, wherein the antiferromagnetic layer is between the top shield and the second ferromagnetic layer; and a shield structure, wherein the read sensor is between the top shield structure and the shield structure.
 11. The magnetic read apparatus of claim 10, wherein the read sensor further comprises a capping layer between the free layer and the first ferromagnetic layer.
 12. The magnetic read apparatus of claim 10, further comprising: a bottom shield abutting a pinning layer of the shield structure; and a side magnetic bias structure located on either side of the read sensor.
 13. The magnetic read apparatus of claim 10, wherein the shield structure comprises a shield pinning structure and a shield reference structure separated by a nonmagnetic coupling layer.
 14. The magnetic read apparatus of claim 13, wherein the shield pinning structure comprises a pinning layer and a magnetic layer between the pinning layer and the nonmagnetic coupling layer.
 15. The magnetic read apparatus of claim 14, wherein the shield reference structure comprises a first magnetic layer, a second magnetic layer and a nonmagnetic layer between the first magnetic layer and the second magnetic layer.
 16. The magnetic read apparatus of claim 13, wherein the shield pinning structure is wider than the shield reference structure in a cross-track direction that is parallel to an air bearing surface.
 17. A magnetic read apparatus comprising: a read sensor; a shield structure; a top shield structure comprising: a first ferromagnetic layer; a second ferromagnetic layer; a nonmagnetic layer between the first ferromagnetic layer and the second ferromagnetic layer; an antiferromagnetic layer; and a top shield, wherein the antiferromagnetic layer is between the top shield and the second ferromagnetic layer; and a bottom shield, wherein the read sensor is between the top shield structure and the shield structure; and wherein the shield structure is between the read sensor and the bottom shield.
 18. The magnetic read apparatus of claim 17, further comprising a capping layer between the read sensor and the first ferromagnetic layer of the top shield structure.
 19. The magnetic read apparatus of claim 17, wherein the shield structure comprises a shield pinning structure and a shield reference structure, and wherein the shield pinning structure is wider than the shield reference structure in a cross-track direction that is parallel to an air bearing surface.
 20. The magnetic read apparatus of claim 19, wherein the bottom shield is wider than the shield pinning structure in the cross-track direction. 